Modern analytical instruments are particularly susceptible to performance variations due to the temperature of certain devices within the system, or to variations in the ambient temperature conditions in which the analytical instrument is operated. Maintenance of the requisite temperature of one or more devices in the instrument is typically accomplished by electrically-powered heating means, such as an electrical resistance heater. Such means require considerable power and accordingly most conventional analytical instruments are operated in a laboratory setting where adequate electrical power is available.
Prior art attempts to adapt an analytical instrument to field-portable use have not been fully successful due in part to an unresolved need for a lightweight, portable, self-contained, and inexpensive energy source for powering a temperature control system. Arrays of lightweight rechargeable batteries have been attempted, but such arrays are expensive, bulky, and have inadequate storage capacity. Larger storage batteries, such as lead-acid batteries, offer greater storage capacity but are heavy, bulky, and subject to leakage of the electrolyte, which is corrosive. The size, weight, and upkeep of a gasoline-powered generator makes it generally impractical for use in nearly all applications, and especially those wherein the analytical instrument is meant to be highly portable, self-contained, and hand-held. Solar energy conversion devices are not a reliable source of energy if not coupled with ancillary equipment, such as storage batteries, to overcome periods without sunshine, and to handle peak current demands.
Accordingly, a need exists for a portable analytical instrument having at least one zone therein that may be selectively heated and/or cooled by use of a temperature control system operating on a truly compact, lightweight, and inexpensive power source.